Hot Gas Defrost Condensate Pan

ABSTRACT

A hot gas defrost condensate pan for collecting condensation from a refrigerator evaporator system is disclosed and claimed. In an embodiment, the condensate pan includes a heat exchanger with a header forming a closed loop and a tube bank disposed within the closed loop. The upper plane of the tube bank sits below the upper plane of the header, forming a recess in which an inner pan section sits. The header and tube bank collectively define a frame for the condensate pan. Further, the header surrounds the perimeter of the inner pan section, providing defrost heat in ice-prone areas. An outer pan section is provided on the underside of the heat exchanger. The inner pan section and the outer pan section are preferably seam welded to the heat exchanger, to protect the internal components of the condensate pan, and to prevent the ingress of dirt and bacteria.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable.

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable.

BACKGROUND OF THE INVENTIONS

1. Technical Field

The embodiments described and claimed herein relate generally to a hot gas defrost condensate pan for a refrigerating evaporator. The hot gas defrost condensate pan includes a hot gas defrost heat exchanger with an improved configuration. More specifically, at least some of the embodiments described herein relate to a hot gas defrost heat exchanger that forms a frame for the condensate pan and/or provides improved defrost characteristics in ice-prone areas of the condensate pan.

2. Background Art

It is well known in the refrigeration art to use “hot gas” refrigerant to melt ice and slush that accumulate in an evaporator condensate pan. In a typical application, the “hot gas” refrigerant is drawn from the compressor outlet or from the liquid receiver, and directed into a heat exchanger placed in or adjacent to the condensate pan. See, for example, U.S. Pat. Nos. 3,451,226, 3,664,150, 4,474,029, and 5,315,836, which are all incorporated herein by reference. Typical prior art hot gas defrost condensate pans lack a frame and are generally constructed using heat exchanger tubes disposed between two thin gauge sheets that are brought together and welded at their perimeter. In these prior art pans, it has been found that ice tends to accumulate at the perimeter and in the corners of condensate pans. The prior art condensate pans have attempted to solve this problem by locating heat exchange tubes near, but inside of, the perimeter of the pan. While these prior art hot gas defrost condensate pans may provide satisfactory defrost characteristics, they do not present the optimal solution to the aforementioned icing problem. Accordingly, there is still a need in the art for a hot gas defrost condensate pan that is effective at melting ice in ice-prone areas.

BRIEF SUMMARY OF THE INVENTIONS

The embodiments described and claimed herein solve at least some of the problems of the prior art.

In one particular embodiment described and claimed herein, a condensate pan for a refrigeration unit is provided with an inner pan section for condensate collection and a heat exchanger that is thermally connected to the inner pan section. The heat exchanger includes at least a first tube extending along a length of the inner pan section, wherein the first tube is positioned and extends outside a perimeter of and along a first side of the inner pan section.

In another particular embodiment, a condensate pan for a refrigeration unit is provided with an inner pan section for condensate collection and a heat exchanger that is thermally connected to the inner pan section. The heat exchanger has a header and a tube bank. The header forms a closed loop and the tube bank is disposed inside of the closed loop and below an upper plane of the header to define a recess in the closed loop. The inner pan section sitting in the recess, whereby the heat exchanger defines a frame for the inner pan section.

In yet another particular embodiment, a condensate pan is provided with an inner pan section thermally connected to a heat exchanger. The heat exchanger has at least one tube extending adjacent to substantially the entire perimeter of the inner pan section, wherein the at least one tube is in thermal contact with the perimeter of the inner pan section. The heat exchanger also includes a tube bank extending underneath and being in thermal contact with the inner pan section.

In each of the three embodiments described above, the edge of the inner pan section is kept warm to prevent or reduce ice accumulation at the perimeter and in the corners of the pan.

Other embodiments, which include some combination of the features discussed above and below and other features which are known in the art, are contemplated as falling within the claims even if such embodiments are not specifically identified or discussed herein.

BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWINGS

These and other features, aspects, objects, and advantages of the embodiments described and claimed herein will become better understood upon consideration of the following detailed description, appended claims, and accompanying drawings where:

FIG. 1 is a perspective view of a first embodiment of a hot gas defrost condensate pan;

FIG. 2 is a top view of the first embodiment;

FIG. 3 is a front view of the first embodiment;

FIG. 4 is a is a first cross-sectional view of the first embodiment along the cross-section identified in FIG. 3;

FIG. 5 is a is a first detail view of the first embodiment at the region highlighted in FIG. 4;

FIG. 6 is a second detail view of the first embodiment at the region highlighted in FIG. 3;

FIG. 7 is a is a side view of the first embodiment;

FIG. 8 is a second cross-sectional view of the first embodiment along the cross-section identified in FIG. 7;

FIG. 9 is a third detail view of the first embodiment at the region highlighted in FIG. 7;

FIG. 10 is a fourth detail view of the first embodiment at the region highlighted in FIG. 7; and,

FIG. 11 is a perspective view of a heat exchanger of the first embodiment with certain portions shown transparent to reveal internal structures of the heat exchanger.

It should be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the embodiments described and claimed herein or which render other details difficult to perceive may have been omitted. It should be understood, of course, that the inventions described herein are not necessarily limited to the particular embodiments illustrated. Indeed, it is expected that persons of ordinary skill in the art may devise a number of alternative configurations that are similar and equivalent to the embodiments shown and described herein without departing from the spirit and scope of the claims.

Like reference numerals will be used to refer to like or similar parts from Figure to Figure in the following detailed description of the inventions.

DETAILED DESCRIPTION OF THE INVENTIONS

A first embodiment of a hot gas defrost condensate pan 10 is shown in FIGS. 1-11. The condensate pan 10 is intended to sit below a refrigeration evaporator (not shown) to collect condensate dripping from the evaporator, and to direct that condensate to a drain. It is contemplated that the condensate pan 10 will be used primarily in process rooms or in hygienic applications, although the scope of the claims are not limited as such. In these applications, accumulation of dirt and growth of bacteria are prime concerns. To keep the room in a sanitary condition, operators often liberally use high pressure spray washes to clean all surfaces of a refrigeration unit, both inside and out. It is therefore important that all components of a refrigeration unit, including the condensate pan 10, be rigidly constructed and fully sealed.

In that regard, the condensate pan 10 comprises five main components: an inner pan section 20, a heat exchanger 40, an outer pan section 60, an internal reinforcement member 80, and insulation 100. It is contemplated that the inner pan section 20, the heat exchanger 40, the outer pan section 60, and the internal reinforcement member 80 will be constructed from stainless steel, although other materials can be used.

The inner pan section 20 sits at the top of the condensate pan 10 and includes a bottom wall 21 with a drain pipe 22, a side wall 23 extending upward from the bottom wall 21, and a lip 24 extending outward from a top edge of the side wall 23. The drain pipe extends through and is fully seam welded to both the inner pan section 20 and the outer pan section 60.

The inner pan section 20, as shown, is rectangular with four sides, although the shape of the inner pan section 20 can be varied depending upon the application without departing from the intended scope of the inventions. The side wall 23 is comprised of a first side wall 25, a second side wall 26, a third side wall 27, and a fourth side wall 28. Each of the first, second, third, and fourth side walls 25, 26, 27, and 28 extend upward from the bottom wall 21 at each respective side of the inner pan section 20. The first side wall 25 is opposite from the second side wall 26, and the third side wall 27 is opposite from the fourth side wall 28. The lip 24 is comprised of a first lip 29, a second lip 30, a third lip 31, and a fourth lip 32. The first, second, third, and fourth lips 29, 30, 31, and 32 extend outward from the respective side wall 25, 26, 27, and 28 of the inner pan section 20.

As best shown in FIG. 11, the heat exchanger 40 is rectangular with four sides, complete with tubing running the length of the pan and being welded into a header, although the shape of the heat exchanger 40, like that of the inner pan section 20, can be varied depending upon the application without departing from the intended scope of the inventions. The heat exchanger 40 includes a header 41 and a tube bank 46. The header 41 includes a first pipe (or tube) 42, a second pipe (or tube) 43, a third pipe (or tube) 44, and a fourth pipe (or tube) 45. The first, second, third, and fourth pipes 42, 43, 44, and 45 joined at their ends to form a closed loop. The first pipe 42 is opposite from the second pipe 43, and the third pipe 44 is opposite from the fourth pipe 45. As shown, the ends of the pipes 42, 43, 44, and 45 are welded together, but can be joined by any means, including through the use of elbows. Alternatively, the pipes 42, 43, 44, and 45 can be formed from a continuous pipe (or tube) that is bent at the corners. In the shown embodiment, the first pipe 42 is formed from two separate pipes that are connected at opposite sides of a round plate or plug 49, which divides the first pipe 42 into an inlet side and an outlet side. An inlet tube 54 is connected to the inlet side of the first pipe 42, and an outlet tube 53 is connected to the outlet side of the first pipe 42.

The tube bank 46 is positioned inside the closed loop of the header 40, and extends from the first pipe 42 to the second pipe 43. The tube bank 46 is comprised of a set of first pass tubes 47 and a set of second pass tubes 48. The first pass tubes 47 extend from the inlet side of the first pipe 42 to the same side of the second pipe 43. The second pass tubes 48 extend from the outlet side of the first pipe 42 to the same side of the second pipe 43. In the shown embodiment, the tube bank 46 comprises a total of four tubes, although any number of tubes can be used. Typically, the quantity will range from four to twenty tubes depending upon the application and size of the heat exchanger 40.

During a hot gas defrost cycle, hot refrigerant enters the inlet side of the first pipe 42 through the inlet tube in direction D₁. The first pipe 42 of the header 41 directs refrigerant flow into the first pass tubes 47 and the third pipe 44. A first metered opening or orifice plate 50 is provided in the inlet side of the first pipe 42 to distribute refrigerant flow between the first pass tubes 47 and the third pipe 44, to prevent refrigerant from bypassing the first pass tubes 47 through the path of least resistance (i.e., the third pipe 44). The orifice plate 50 could alternatively be disposed in the third pipe 44, or the inlet side of the second pipe 43. After leaving the inlet side of the first pipe 42, refrigerant travels through the third pipe 44 and the first pass tubes 47 in the directions D₂, D₃, and D₄, and enters the inlet side of the second pipe 43. The second pipe 43 directs refrigerant flow into the second pass tubes 48 and the fourth pipe 45. Refrigerant travels in directions D₅, D₆, and D₇ through the second pass tubes 48 and the fourth pipe 45, and into the outlet side of the first pipe 42. A second metered opening or orifice plate 51 is provided in the outlet side of the first pipe 42 to distribute refrigerant flow between the second pass tubes 48 and the fourth pipe 45, to prevent refrigerant from bypassing the second pass tubes 48 through the path of least resistance (i.e., the fourth pipe 45). The orifice plate 51 could alternatively be disposed in the fourth pipe 45, or the outlet side of the second pipe 43. Flow leaves the outlet side of the first pipe 42 through the outlet tube 53 in direction D₈. As reflected in FIGS. 6 and 11, the outlet tube 53 extends into the lower half of the outlet side of the first pipe 42 to ensure that pooled liquid condensate refrigerant is drawn out of the heat exchanger 40, and includes an angled edge to create venturi effect to pull liquid and any oil out of the heat exchanger 40. To be clear, it is contemplated that refrigerant flow in the heat exchanger 40 could be reversed, e.g., by swapping the locations of the inlet tube 54 and the outlet tube 53. It is also contemplated that the inlet tube 54 can be located at one side of the header 41, e.g. at the first pipe 42, with the outlet tube 53 located at the other side of the header 41, e.g., at the second pipe 43. Of course, for such a configuration, the plug 49 would need to be eliminated.

The header 41 of the heat exchanger 40 serves multiple purposes, including: to support and provide rigidity for the condensate pan 10, to distribute refrigerant to the tube bank 46, and to provide defrost heat to the perimeter of the bottom wall 21 and the side walls 23 of the inner pan section 20, both being ice-prone areas of the condensate pan 10, to ensure that the outer portion of the frame is warm during defrost cycles.

The header 41 and tube bank 46 are rigidly constructed to define a frame for the condensate pan 10, and more particularly, for the inner pan section 20. As shown, the header 41 is constructed from larger diameter pipe (or tube) than the tube bank 46. In one embodiment, the header is formed from 1¼″ NPS schedule 40 stainless steel pipe and the tube bank 46 is formed from 15 mm (0.59″) OD stainless steel tubing. To be clear, other sizes of pipe and tube may be used depending upon the application and the overall dimensions of the pan. For example, some embodiments may use 2″ NPS schedule 10 stainless steel pipe and 22 mm (0.866″) OD stainless steel tubing. It has been found that construction and assembly of the heat exchanger 40 may be simplified by using rectangular tube for the header 41. Of course, because rectangular tube can withstand less pressure, the walls of the rectangular tube will need to be thicker than corresponding round tube.

As best shown in FIG. 4, the upper plane of the tube bank 46 sits below the upper plane of the header 41 to define a recess 55 inside of the closed loop of the header 41. As best shown in FIGS. 4 and 8, the inner pan section 20 sits inside of the recess 55 of the heat exchanger 40. To be clear, a recess can be accomplished by means other than varying the pipe/tube diameter. For example, the tube bank could include downward bends to form the recess.

Collectively, the header 41 and tube bank 46 of the heat exchanger 40 provide defrost heat to the inner pan section 20, to melt ice and slush. The header 41 and tube bank 46 also serve a dual purpose: providing support for the inner pan section 20. As best shown in FIGS. 4 and 5, the tubes of the tube bank 46 are positioned underneath, and therefore support, the bottom wall 21 of the inner pan section 20. The tubes are also in thermal communication with the bottom wall 21, through direct contact or through some other low resistance connection, such as thermopaste 82. As best shown in FIGS. 4, 6, and 8, the header 41 is positioned adjacent to and outside of, and therefore supports, the side wall 23 of the inner pan section 20. As best shown in FIGS. 4, 6, 8, and 9, the header 41 is also positioned underneath, and therefore supports, the lip 24 of the inner pan section 20. The header 41 is in thermal communication with both the side wall 23 and lip 24 of the inner pan section 20, and is fully seam welded to the lip 24 of the inner pan section 20.

The shown embodiment utilizes four hangers 56 for supporting the condensate pan 10 in a refrigeration unit, although any number may be used. The hangers 56 extend through the inner pan section 20 and are welded to the header 41 of the heat exchanger 40. The hangers 56 are also fully seam welded to the inner pan section 20.

As best shown in FIGS. 4 and 5, at least one internal reinforcement member 80 is provided which includes a plurality of “U” clips 81 that receive each tube of the tube bank 46. Thermopaste 82 is applied inside of each clip 81, surrounding each tube, to ensure good thermal connection between the tube bank 46 and the bottom wall 21 of the inner pan section 20. Insulation 100, such as armaflex, is applied to the condensate pan 10 underneath the internal reinforcement member 80 (opposite the tube bank 46), wherein the internal reinforcement member 80 prevents insulation 100 from interrupting good thermal connection between the tube bank 46 and the bottom wall 21. The internal reinforcement member 80 also provides additional support and rigidity for the condensate pan 10.

As best shown in FIGS. 3, 4, 7, and 8, an outer pan section 60 is provided on the underside of the condensate pan 10. Like the inner pan section 20 and the heat exchanger 40, the outer pan section 60, as shown, is rectangular in shape with four sides, but its shape can be varied depending upon the application without departing from the intended scope of the inventions. The outer pan section 40 includes a bottom wall 61 and an angled side wall 62. As best shown in FIGS. 6 and 10, heat exchanger 40 sits inside of the outer pan section 60, with the side wall 62 disposed adjacent outside and to the header 41. The outer pan section 60 is fully seam welded to the heat exchanger 40 at the side wall 62.

The inner pan section 20 and the outer pan section 60 collectively provide a housing for the tube bank 46 of the heat exchanger 40, the internal reinforcement member 80, and the insulation 100, to protect those components during, for example, operation, cleaning, and maintenance. Because the inner pan section 20 and the outer pan section 60 are fully seam welded to the header 41 of the heat exchanger 10, to the drain pipe 22, and to the hangers 56 the condensate pan 10 is fully sealed to prevent ingress of dirt and bacteria.

Although the inventions described and claimed herein have been described in considerable detail with reference to certain embodiments, one skilled in the art will appreciate that the inventions described and claimed herein can be practiced by other than those embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 

We claim:
 1. A condensate pan for a refrigeration unit comprising: an inner pan section for condensate collection, the inner pan section being thermally connected to a heat exchanger; the heat exchanger comprising at least a first tube extending along a length of the inner pan section, wherein the first tube is positioned and extends outside a perimeter of and along a first side of the inner pan section.
 2. The condensate pan of claim 1, wherein the inner pan section comprises a bottom wall; the heat exchanger comprises a tube bank; and, the tube bank is thermally connected and disposed adjacent to an underside of the bottom wall.
 3. The condensate pan of claim 2, wherein the inner pan section comprises a first wall extending upward from the bottom wall at the first side; and, the first wall is thermally connected and disposed adjacent to the first tube.
 4. The condensate pan of claim 3, wherein the inner pan section comprises a first lip extending outward from a top of the first wall; and, the first lip is thermally connected and disposed adjacent to the first tube.
 5. The condensate pan of claim 2, wherein the inner pan section comprises a second side, a third side, and a fourth side; the heat exchanger also comprises a second tube being positioned and extending along the second side of the inner pan section, a third tube being positioned and extending along the third side of the inner pan section, and a fourth tube being positioned and extending along the fourth side of the inner pan section; and, the first tube, the second tube, the third tube, and the fourth tube are interconnected to form a closed loop with at least a portion of the inner pan section resting inside of the closed loop.
 6. The condensate pan of claim 5, wherein the first tube, the second tube, the third tube, and the fourth tube collectively form a header for the heat exchanger to distribute refrigerant to the tube bank.
 7. The condensate pan of claim 6, wherein the tube bank is disposed below an upper plane of the header to form a recess, and the bottom wall of the inner pan section is supported by the tube bank within the recess.
 8. The condensate pan of claim 7, wherein the inner pan section comprises a first wall extending upward from the bottom wall at the first side, a second wall extending upward from the bottom wall at the second side, a third wall extending upward from the bottom wall at the third side, and a fourth wall extending upward from the bottom wall at the fourth side; the first wall is thermally connected and disposed adjacent to the first tube, the second wall is thermally connected and disposed adjacent to the second tube, the third wall is thermally connected and disposed adjacent to the third tube, and the fourth wall is thermally connected and disposed adjacent to the fourth tube.
 9. The condensate pan of claim 8, wherein the inner pan section comprises a first lip extending outward from a top of the first wall, a second lip extending outward from a top of the second wall, a third lip extending outward from a top of the third wall, and a fourth lip extending outward from a top of the fourth wall; and, the first lip is thermally connected and disposed adjacent to the first tube, the second lip is thermally connected and disposed adjacent to the second tube, the third lip is thermally connected and disposed adjacent to the third tube, and the fourth lip is thermally connected and disposed adjacent to the fourth tube.
 10. The condensate pan of claim 9, wherein an underside of the first lip rests atop the first tube, an underside of the second lip rests atop the second tube, an underside of the third lip rests atop the third tube, and an underside of the fourth lip rests atop the fourth tube, whereby the first tube, the second tube, the third tube, and the fourth tube collectively support the inner pan section.
 11. The condensate pan of claim 1 further comprising an outer pan section, wherein the inner pan section and the outer pan section collectively define a housing for the condensate pan.
 12. The condensate pan of claim 1, wherein the first tube has a rectangular cross-section.
 13. A condensate pan for a refrigeration unit comprising: an inner pan section for condensate collection, the inner pan section thermally connected to a heat exchanger; the heat exchanger having a header and a tube bank; the header forming a closed loop; the tube bank being disposed inside of the closed loop and below an upper plane of the header to define a recess in the closed loop; and, the inner pan section sitting in the recess, whereby the heat exchanger defines a frame for the inner pan section.
 14. The condensate pan of claim 13, wherein the inner pan section has a bottom wall with a drain opening and a side wall extending upward from a perimeter of the bottom wall; the bottom wall is positioned adjacent to the tube bank; and, the side wall is positioned adjacent the header.
 15. The condensate pan of claim 14, wherein an upper surface of the tube bank is thermally connected to and supports the bottom wall.
 16. The condensate pan of claim 15, wherein an inner surface of the header is thermally connected to and supports the side wall.
 17. The condensate pan of claim 16, wherein the inner pan section has a lip extending outward from a top of the side wall; and, the lip is positioned adjacent to the header.
 18. The condensate pan of claim 17, wherein an upper surface of the header is thermally connected to and supports the lip.
 19. The condensate pan of claim 13, wherein the header is rectangular-shaped with a first header tube, a second header tube, a third header tube, and a fourth header tube; the first header tube is opposite the second header tube and the third header tube is opposite the fourth header tube; and, the tube bank extends between the first header tube and the third header tube.
 20. The condensate pan of claim 19, wherein an inlet tube and an outlet tube are connected to the first header tube of the header; and, the header includes an internal plug between the inlet tube and the outlet tube to prevent short circuit of refrigerant from the inlet tube to the outlet tube.
 21. The condensate pan of claim 20, wherein tube bank includes a plurality of first pass tubes and a plurality of second pass tubes; the header includes a first internal orifice plate positioned downstream of the inlet tube to distribute flow between the third header tube and the plurality of first pass tubes; and, the header includes a second internal orifice plate positioned upstream of the outlet tube to distribute flow between the fourth header tube and the second pass tubes.
 22. The condensate pan of claim 20, wherein a cross-sectional area of the header is larger than a cross-sectional area of each of the first pass tubes and the second pass tubes.
 23. The condensate pan of claim 13 further comprising an outer pan section attached to an underside of the heat exchanger, wherein the inner pan section and the outer pan section collectively define a housing for the condensate pan.
 24. The condensate pan of claim 13, wherein header has a rectangular cross-section.
 25. A condensate pan comprising: an inner pan section thermally connected to a heat exchanger, the inner pan section having a perimeter; the heat exchanger comprising at least one tube extending adjacent to substantially the entire perimeter of the inner pan section, wherein the at least one tube is in thermal contact with the perimeter of the inner pan section; the heat exchanger further comprising a tube bank, wherein the tube bank extending underneath and is in thermal contact with the inner pan section.
 26. The condensate pan of claim 25, wherein the at least one tube forms a closed loop, surrounds the perimeter of the inner pan section, and defines a frame for the inner pan section.
 27. The condensate pan of claim 26, wherein the at least one tube serves as a header for the tube bank; the tube bank being disposed underneath an upper plane of the at least one tube, wherein the at least one tube and the tube bank collectively define a recess in which the inner pan section rests.
 28. The condensate pan of claim 25, wherein the at least one tube has a rectangular cross-section. 